In recent years, since carbon dioxide emission to the atmosphere resulting from combustion of fossil fuels may significantly affect an ecosystem and the global environment, a reduction in the emission of carbon dioxide is desired globally.
Accordingly, a technique for eliminating the emission of carbon dioxide or reducing the emission amount of carbon dioxide is developed and, as part of the development, a technique for fixing carbon dioxide and a technique for converting carbon dioxide to other compounds are also developed.
In addition, in a completely closed environment such as a space station or a rocket, it is not easy to supply substances, and it is necessary to minimize the supply or emission at an element level.
Accordingly, it is desired to convert produced carbon dioxide to another substance to increase a substance that can be recovered and reduce a supplied or emitted substance as much as possible at the element level.
As a method for alleviating the amount of carbon dioxide in the atmosphere, a method for capturing carbon dioxide and burying it in the ground is specifically promoted.
In addition, there is an attempt to cause carbon dioxide to react with hydrogen by the Sabatier reaction at a high temperature in the vicinity of 300° C. to produce methane, recover the methane, and use the methane as energy that can be readily transferred.
However, each of these methods is a method that injects a large amount of energy for the burial or a method that requires energy for maintaining the high temperature.
As a method and system that suppresses the injection of energy and fixes carbon dioxide, there are proposed a solid polymer power generation method and system that, while generating electricity by a fuel cell reaction with carbon dioxide used as an oxidizing agent by supplying carbon dioxide to the cathode side of a reactor having a membrane electrode assembly provided with a catalyst layer and supplying hydrogen to the anode side thereof, produces an available compound other than carbon monoxide or the like by reducing carbon dioxide during the reaction, and allows recycling of carbon resources (see, e.g., PTL 1 or the like), and a solid polymer electrolysis method and system that supplies water vapor or liquid water, produces a hydrogen ion by electrolyzing the water vapor or liquid water, and uses the hydrogen ion in the reduction reaction of a carbon dioxide gas (see, e.g., PTL 2 or the like).